Some tips from Carmen - I store it in the freezer in a ziploc bag. I use brown rice flour because it offers more vitamins, minerals, and fiber. The potato starch flour is used to help baked foods have a lighter texture and maintain moisture. Tapioca flour is used to lighten bake goods and help them brown. It also makes the items a little chewy. Garbanzo bean flour adds protein. Cornstarch has no nutritional value but helps with texture. Xanthan (pronounedzan-thun) gum helps hold the baked goods together. Can substitute unflavored gelatin for xanthan gum. If the recipe calls for 1 teaspoon of xanthan gum use 2 teaspoons of unflavored gelatin. Xanthan gum runs about $14 per pound. I keep it in the fridge and a pound lasts about a year for me.